1. Technical Field
Example embodiments of the present invention relate in general to wireless communication technology, and more specifically, to a secure communication method and system that can be applied to a network environment in which a transmitter does not know channel information of a wiretapper.
2. Related Art
A wireless communication system is a system that transmits and receives a signal through air. The wireless communication system uses air that is an opened medium, and thus, when an unauthorized user knows processing information on a transmission signal, there is a risk in which the unauthorized user wiretaps the transmission signal and easily acquires secret information.
As the concept of a secrecy capacity is introduced to a wireless communication environment in which there is a wiretap channel, research related to secure technology is started to be conducted in a physical layer of the wireless communication system.
Generally, the secrecy capacity is a value that is obtained by subtracting a transmittable channel capacity between a transmitter and a wiretapper from a transmittable channel capacity between the transmitter and a receiver.
However, in a wireless communication channel, since a channel state is frequently changed, the secrecy capacity of the wiretap channel frequently has a positive value and a value of 0.
As described above, a method of installing and using a helper node has been proposed to overcome the limitation of a channel capacity that is changed depending on a channel condition and provide a stable secrecy capacity.
Korean Unexamined Patent Application Publication No. 10-2008-67680 discloses a secure communication method in which that a first transmitter transmits a noise signal through a communication channel having a range used by a receiver in order to provide secure communication with no encryption, and the receiver receives information transmitted by a second transmitter through one or more communication channels having a certain range and distinguishes transmission by the second transmitter from the noise signal by using information provided from the first transmitter on the noise signal.
However, in Korean Unexamined Patent Application Publication No. 10-2008-67680, the secure communication method cannot be performed when the first transmitter does not know communication channel information of the receiver, and moreover, since the first transmitter needs to separately provide noise signal information to the receiver, an overhead increases.